Most sexually transmitted diseases are caused by bacteria or viruses, but some are caused by organisms that are classified as completely different lifeforms. Trichomoniasis, for example, is caused by a protozoan organism; protozoa occupy their own kingdom, separate from plants, animals, and bacteria. Intestinal parasites are often protozoan organisms, but can also include parasitic worms (which are members of the animal kingdom). They are spread through contact with fecal matter — and as such, they can be transmitted sexually as well as nonsexually. Intestinal parasites are usually transmitted by fecal contamination of food or water, and are most common in areas with insufficient sewage treatment and untreated water in the wilderness. Some pathogens, however, have low infectious doses, making their sexual transmission more likely.

What has eight flagella and can live in your intestines?

Oral contact with the anus, also called anilingus or rimming, is the primary means of the sexual transmission of these pathogens. Putting fingers or hands in your mouth after they have had contact with the anus is also risky. Other modes of transmission include oral sex, as genitals can be contaminated with feces, as well as sharing sex toys and other equipment. For these reasons, it is very important to use dental dams or latex gloves during contact with the anus; to clean the anus before engaging in rimming; to clean or use condoms on shared sex toys; and to use condoms or dental dams during oral sex. Continue reading →

Most sexually transmitted diseases are caused by viruses or bacteria. STDs caused by viruses include herpes and genital warts, and the viruses that cause them aren’t even technically living organisms — they are pieces of genetic information that are able to infect a host cell. STDs caused by bacteria include gonorrhea and syphilis; bacteria are microscopic, single-celled organisms with relatively simple cell structures.

But some STDs are caused by other types of living organisms. Protozoan organisms are microscopic and unicellular, like bacteria; unlike bacteria, their cell structures more closely resemble that of the so-called “higher” life forms such as animals and plants. While protozoa are considered to be “animal-like,” they are not animals at all — they are single-celled organisms that reproduce asexually. When certain types of protozoans get into your body, they can cause infections — such as trichomoniasis, the most common curable STD among young females (as well as more females over 40 than previously thought). It is estimated that 7.4 million new cases of trichomoniasis occur annually in the United States; worldwide, there are about 170 million cases each year.

Trichomoniasis, colloquially known as trich, is spread by vaginal or anal intercourse, direct vulva-to-vulva contact, and other activities that involve passing secretions from one partner to another (e.g., sharing sex toys or mutual masturbation). Sexually active people can reduce the risk of contracting trichomoniasis by using latex barriers, such as condoms. Continue reading →

Neisseria gonorrhoeae, which causes gonorrhea, is pictured here in a photograph taken with a scanning electron microscope. Projecting from the organism’s surface are many pili, powerful appendages that enable the bacteria to adhere to human cells. Image: National Institute of Biomedical Imaging and Bioengineering.

April is STD Awareness Month, but this blog has sought to increase your awareness of sexually transmitted diseases on a monthly basis. So far in 2011 we’ve pointed the spotlight at human papillomavirus, barrier methods, and herpes. This month’s installment will focus on gonorrhea, colloquially known as “the clap,” a common sexually transmitted disease caused by sneaky bacteria called Neisseria gonorrhoeae. It is spread by vaginal, anal, and oral sex, and can infect certain cells in the throat, mouth, rectum, urethra, or cervix. It can also be transmitted manually to infect the eye. If you are sexually active, you can reduce risk of transmission by consistently and correctly using latex barriers such as condoms and dental dams.

Four out of five females infected with gonorrhea do not experience symptoms – males, however, usually do, but they can be mild and therefore easy to overlook. Symptoms can appear within a month, and might include painful or frequent urination, vaginal or penile discharge, painful bowel movements, itching, or sore throat. Additionally, females can experience abdominal pain, fever, irregular menstruation, or bleeding between periods. In pregnant women, untreated gonorrhea infections can lead to complications such as premature labor or stillbirth. The infection can also be passed from mother to infant during delivery. Continue reading →